High luminance light sources are employed in a very wide variety of fields, for instance in endoscopy as well as in projection apparatus, gas discharge lamps currently being the most widespread. The most recent developments in this field relate to the combination of a high power density light source, for instance a laser, with a luminescent element which converts pump light and is arranged at a distance from the pump light source. By means of the luminescent element, conversion of e.g. ultraviolet or blue pump light into longer wavelength converted light is carried out, during which a power loss emitted in the form of heat typically always occurs, for instance owing to the Stokes shift. For this reason, a luminescent element is often operated in reflection, i.e. the pump light is shone in in one direction and the converted light is emitted in the opposite direction, so that a heat sink can be provided on the rear side of the luminescent element.